Lung cancer is one of the leading causes for morbidity and mortality related with cancer worldwide. Also known as bronchogenic carcinoma, lung cancer is any cancer that arises from the bronchi or from the lung parenchymal tissue. A gene locus that determines vulnerability to lung cancer has been described. The causes of cancer include environmental carcinogens such as asbestos, as well as cigarette smoking (Chirieac & Kobzik, 2017). The latter has been identified as the main etiology for lung cancer. There are various types of lung cancer, based on pathological classification. These include small cell lung cancer, squamous cell carcinoma, and adenocarcinoma. A clear understanding of the pathophysiology of lung cancer is crucial for proper diagnosis and management.
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The pathophysiology of all types of lung cancers is related to either the inactivation of tumor-suppressor genes or the activation of oncogenes by various carcinogens. The mutations that are caused by the carcinogens or the tumor-suppressor genes lead to the development of the cancerous cells. Close to 30 percent of all adenocarcinomas are caused by mutations in the proto-oncogene known as K-ras. Inactivation of the tumor-suppressor genes may result from epigenetic changes such as histone modification or DNA methylation (Zheng, 2016). The epidermal growth factor receptor plays a role in the regulation of tumor invasion and apoptosis. Small cell carcinomas of the lung cause mutation of the epidermal growth factor receptor (EGFR).
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The classical pathophysiology of lung cancer usually starts with the introduction of the carcinogen into the lung. This carcinogen may accumulate to a level where it causes obstruction of the walls of the lung. The next stage is the development of the obstructive emphysema of the lung. The resulting infection of the lob transforms into abscess formation. The abscess then enlarges and involves the pleura of the lung. The next stages are the extension to the chest wall which leads to the inversion of the bronchi or the intercostal nerves. This process leads to extreme compression of neighboring structures. The patient presents with severe chest pains, as well as severe difficulty in breathing. The lung cancer may then metastasize to other regions.
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